The document discusses key concepts from the theory of relativity, including: 1) The Michelson-Morley experiment failed to detect the "aether wind" and proved that the speed of light is constant regardless of the motion of the observer. 2) According to relativity, time dilation and length contraction occur so that the speed of light remains constant, and simultaneity is relative to the observer's frame of reference. 3) Key consequences of relativity include that moving clocks run more slowly and the length of objects decreases as their speed increases.

1. Theory of relativity
C.SRAVYA
A.LAKSHMI MANASA

2. KEYPOINTS:
 What is relativity?
 The most famous “failed” experiment
 Speed of light is constant
 Time dilation
 Relativity of simultaneity
 Length contraction

3. What is relativity?
 The way that anything except light moves
through time and space depends on the
position and movement of someone who
is watching.

4. MICHELSON-MORLEY
EXPERIMENT
 Experiment performed for the detection of
“aether wind”.
 Comparison of speed of light in
perpendicular directions.
 The failure initiated research which led to
proposal of theory of relativity.

5. MICHELSON – MORLEY
EXPERIMENT
 The failure of
this experiment
proved that
speed of light is
constant.

6. Speed of light is constant
As seen by out fielder, ball is
approaching her at 30m/s + 10m/s =
40m/s

7. Speed of light is constant
Incorrect Newtonian description:
As seen by astronaut in spaceship, light
is approaching her at 3 × 108 + 1 × 108 = 4 ×
108m/s
Correct Einsteinian description:
As seen by astronaut in spaceship, light is
approaching her at 3 × 108 m/s

8. Facts and consequences
 Facts:
 Regardless of speed and direction, observers
always measure the speed of light to be the
same value.
 Speed of light is the maximum possible
speed.
 Consequences:
The length of an object decreases as its
speed increases.
 Clocks passing by you run more slowly than
do clocks at rest

9. TIME DILATION
L
vt

10. How fast does time slow?
 Assumption:
Two observers are in
relative uniform motion v
uninfluenced by gravitational
mass.
 Effect:
The other clock is ticking at
a slower rate than the local
clock.
t’ = t√1-(v/c)2

11. Simultaneity
 Light in center of car
flashes, hits front and
back simultaneously.
 To an observer
watching the car move,
the car travels while the
light is in motion. So
the light hits the back of
the car before the front

12. Length Contraction